In a semiconductor manufacturing process, a plasma processing apparatus that executes a plasma processing for the purpose of, for example, deposition of a thin film or etching has been widely used. As the plasma processing apparatus, a plasma chemical vapor deposition (CVD) apparatus that performs a deposition processing of a thin film or a plasma etching apparatus that performs an etching processing may be exemplified.
The plasma processing apparatus includes a processing container configured to define a plasma processing space, a mounting table configured to mount a to-be-processed substrate thereon within the processing container, an upper electrode provided above the mounting table, and a gas supply system configured to introduce a processing gas required for a plasma reaction into the processing container. In addition, in order to turn the processing gas within the processing chamber into plasma, the plasma processing apparatus includes, for example, a plasma generation mechanism configured to supply electronic energy such as for example, microwaves or RF waves. In addition, in the plasma processing apparatus, an exhaust flow path for exhausting the processing gas to the outside of the processing container is formed by the side wall of the processing container and the side surface of the mounting table. In the exhaust flow path, a baffle plate is provided to adjust the flow of the processing gas. The baffle plate functions to rectify the gas within the processing container so as to cause the gas to be uniformly exhausted. In addition, the baffle plate usually has conductivity.
However, in the plasma processing apparatus, it has been known that electrons in the generated plasma are drawn to the conductive baffle plate and produce a reaction product on the surface of the baffle plate. Thus, a conductor is provided in the exhaust flow path in order to block the electrons. For example, there is a prior art in which a ground electrode made of a conductor is arranged in the exhaust flow path at a position that is higher than the baffle plate and lower than a to-be-processed substrate mounted on the mounting table so as to cause the electrons in the plasma to escape to the ground electrode. See, for example, Japanese Patent Laid-Open No. 2007-258471.